Due to the large amount of information being transferred over Synchronous Optical Networks (SONET), there is a large financial stake in ensuring that the data transport services are as readily and, more importantly, consistently available as possible. To better insure consistent data transmission, SONET equipment is employed in a number of configurations that provide redundant transmission paths. If a fault does occur in any of these paths, the network can rapidly perform what is called a “protection switch.” In a protection switch, the network moves data transmission from a line on which a fault has been detected to a redundant backup transmission line to avoid any interruption in data transmission. The protocol that governs the switching between redundant data transmission lines is referred to as Automatic Protection Switching (APS).
FIG. 1 illustrates a piece of telecommunications equipment (100) that is part of a synchronous optical network. The equipment (100) is connected to the network through a SONET optical interface (101). The interface (101) includes two connections (102, 103) with which the interface (101) can be connected to two redundant data transmission lines. One of the connections is typically referred to as the “working” connection (102). The other is typically referred to as the “protect” connection (103).
Data transmission is usually carried through the working connection (102) of the interface (101). However, under the APS protocol, if a fault is detected on the working or main line (102), the interface (101) can switch to using the protect connection (103) and the data line accessed through that connection to protect against any interruption in data flow.
FIG. 2 more fully illustrates an exemplary SONET optical network. As shown in FIG. 2, two pieces of telecommunications equipment (100a, 100b) are connected through a synchronous optical network, represented by two redundant data lines (104, 105). Each piece of equipment (100a, 100b) has a SONET optical interface (101a, 101b) for connection to the optical network.
As described above, each optical interface (101a, 101b) has two connections: one for a working or main line (102a, 102b) and one for a protect or backup line (103a, 103b). To prevent any loss of data transmission, if a fault is detected on the working or main line (104), data transmission can be switched to the protect or backup line (105). However, for this redundant data transmission system to work, there must be interoperability between the two optical interfaces (101a and 101b). For example, both interfaces (101a, 101b) must agree on when a fault has occurred such that data transmission will be switched from one line (104) to the other (105). Both interfaces (101a, 101b) must agree on when the fault has cleared and data transmission can be resumed on the main line (104). In other words, there must be compatibility in the APS protocol running on each of the two interfaces (101a, 101b).
However, optical SONET interfaces are currently being produced by many different network device manufacturers. Consequently, the equipment produced may incorporate varying interpretations of the APS protocol standards and other relevant specifications. The equipment may also vary as to the degree the APS protocol and other specifications are implemented.
With enormous interconnection requirements between equipment from different vendors of these optical interfaces, interoperability has become a major problem for service providers. The fact that there are some equipment manufacturers with little to no experience in the telecommunications field compounds this problem. As a result, a great deal of testing is required to ensure that the equipment not only complies with the relevant standards, but also that it will successfully interoperate with the numerous other devices that comprise the network.
It would be very advantageous to the service provider to be able to perform such compatibility tests in a controlled environment before actually connecting the devices in the field. However, the surest current method of testing these optical devices is to gather all of the necessary pieces of equipment, i.e., all the equipment that will be used in the network, and then assemble a model network in a lab. At a minimum, this would require assembling a network such as that illustrated in FIG. 2. However, it is much more likely that the interoperability of more than just two interfaces (e.g., 101a, 101b) may have to be checked.
After the sample network is constructed the relevant tests can be performed to insure the interoperability of all the network components, particularly the SONET optical interfaces. The problem with this method of testing for interoperability is that a service provider typically only has access to the equipment that will reside on its own end of the network. It is difficult and expensive to also procure the equipment that will be used at one or more customer sites merely for the purpose of assembling a test network in which interoperability of network interfaces can be verified.
Consequently, there is a great need in the art for a means and method of determining the interoperability of optical network interfaces without having to assemble a test network including all the anticipated components that must successfully work together.